Hydraulic vane machine with controlled vanes

ABSTRACT

The rotor of a vane pump or hydraulic motor, has vane slots in which the inner ends of vanes form bottom chambers, while the outer ends project from the rotor and form intervane space with the inner surface of a surrounding cam ring. Two throttles are mounted in the rotor on opposite sides of each vane slot and have inner ends communicating with the respective bottom chamber and outer ends communicating with two adjacent intervane chambers. When a vane passes through a flow reversing zone, different pressures prevail in the respective pair of leading and trailing intervane spaces so that fluid flows through the respective throttles and bottom chamber. In this manner, an intermediate gradually changing pressure acts in the respective bottom chamber to urge the vane outward to engage the cam ring.

1111 3,813,194 14 1 May28, 1974 HYDRAULIC VANE MACHINE WITH CONTROLLED VANES [75] lnventor: Joerg Scholz, Lohr, Germany [73] Assignee: G. L. Rexroth' GmbH, Lohr/Main,

. Germany [22] Filed: Nov. 3, 1972 [21] Appl. N0.: 303,633

[30] Foreign Application Priority Data 3,627,456 12/1971 Gerlach ..4l8/82 Primary ExaminerC. J. Husar Attorney, Agent, or Firm-Michael S. Striker 57] ABSTRACT The rotor of a vane pump or hydraulic motor, has vane slots in which the inner ends of vanes form bottom chambers, while the outer ends project from the rotor and form intervane space with the inner surface of a surrounding cam ring. Two throttles are mounted in the rotor on opposite sides of each vane slot and have inner ends communicating with the respective bottom chamber and outer ends communicating with two adjacent intervane chambers. When a vane passes through a flow reversing zone, different pressures prevail in the respective pair of leading and trailing intervane spaces so that fluid flows through the respective throttles and bottom chamber. in this manner, an intermediate gradually changing pressure acts in the respective bottom chamber to urge the vane outward to engage the cam ring.

' l 7 HYDRAULIC VANE MACHINE WITH CONTROLLED VANES BACKGROUND OF THE INVENTION The present invention relates to vane machines such as a vane pump or vane motor. In order to obtain a good efficiency, it is of importance in machines of this type that the high pressure conduits and low pressure conduits are reliably sealed from each other. This requires a tight engagement of the outer ends of the vanes with the inner surface of the surrounding cam ring, particularly in the zone in which the expanding intervane spaces begin to contract, and which is located between the inlet and outlet ports.

It is known to apply the, high pressure of a pump outlet, or of a hydraulic motor inlet, to bottom chambers formed in the vane slots by the vanes for urging the vanes outward into sealing engagement with the inner surface of the eccentric cam ring. It has been proposed to provide-high pressure ports in lateral end plates or control plates, at the level of the inner ends of the vane slots in the rotor. The apparatus of the prior art'causes the sudden application of high pressure to a vane passing from the low pressure port to the high pressure port so that the outer end of the respective vane is pushed with great force against the inner surface of thecam ring, causing great operational noise, and resulting in great wear of the inner surface of the cam ring in this region, and also wear of the outer ends of the vanes.

It has also been proposed to hydraulically balance the vanes by connecting channels between the bottom chamber in the respective vane slot, and the respective intervane space, while the required sealing force is obtained by small pistons'whose cylinders receive pressure fluid from the high pressure conduit of the hydraulic machine, and acting on the inner end of the vane. A result of this arrangement is that the vanes are pressed by the small pistons with full force against the inner surface of the cam ring, although in the region of the inlet and outletports, no such great force is required for sealing theouter ends of'the vanes engaging the cam ring. i

SUMMARY OF THE INVENTION necessary for sealing, and not so great as to cause wear of the engaging parts.

Another object of the invention isto exert only little pressure on the vanes moving along the inlet and outlet ports of the hydraulic vane machine, but being pressed by a suitable pressure against the eccentric cam ring in the region between the ends of the inlet and outlet ports. 1

Another object of the invention is to avoid that excessive pressure is suddenly applied to a vane'moving from a low pressure port to a high pressure port.

With these objects in view, the present invention provides a flow through a first throttle into a bottom chamber of a valve slot, and from there through a second throttle to a region of lower pressure. In this manner, by dimensioning the throttles, the intermediate pressure acting in the bottom chamber of the vane slot and on the vane, can be exactly detennined. By suitably dimensioning the two throttles, the right pressure in the bottom chamber acting on the vane can be obtained.

In the preferred embodiment of the invention, the bottom chamber in each vane slot is connected by a throttle with the leading and trailing intervane spaces, and the flow cross section of each throttle is influenced and varied by a valve element operated by the pressure of the fluid passing through the throttles.

The communication between the bottom chamber with the intervane spaces trailing and leading the respective vane, has the advantage that in the intervane space in which the lower pressure prevails, the pressure rises in the intermediate zone before the respective intervane space enters the region where the high pressure of the vane machine prevails. In this manner, the noise level of the hydraulic vane machine, and also the pressure drop between the respective intervane space and the pressure zone, which influences the wear, can be reduced.

It is advantageous that the throttles are mounted in bores in the rotor, and have valve seats cooperating with valve elements in the form of spherical balls. The valve seat has one or several transverse channels which form a throttle having a smaller cross section than the main throttling passage.

. The novel features which are considered as characteristic for the invention are set forth in particular in the appended claims. The invention itself, however, both as to its construction and its method of operation, together with additional objects and advantages thereof, will be best understood from the following description of specific embodiments when read in connection with the accompanying drawing.

BRIEF DESCRIPTION OF THE DRAWING FIG. 1 is a fragmentary, partly schematic, plan view, partially in section, illustrating a hydraulic vane machine including a preferred embodiment of the invention; and

. FIG. 2 is a fragmentary horizontal plan view illustrating a detail of FIG. 1 on an enlarged scale.

DESCRIPTION OF THE PREFERRED EMBODIMENTS A rotor 1 is surrounded by an eccentric cam ring 2 whose center is spaced the distance e from the axis A of rotor 1. An arrow 6 indicates the direction of rotation of rotor 1. A stationary valve plate 3 has two partcircular control ports 4 and 5, and it can be assumed that control port 4 is a suction port, and control port 5 is a pressure port. The ends 5a and4b of the ports 4 and5 are spaced from each other, and the ends 4a and 5b of the'ports 4 and 5 are also spaced from each other so that two diametrically opposite intermediate zones 13 are formed between the ports 4 and 5.

Rotor 1 has substantially radial uniformly circumferentially spaced vane slots which are schematically shown, except for three vane slots 7', 7' and 7". Vanes 8, 8 and 8" are located in the respective vane slots 7, 7 and 7", projecting outward from the outer surface of rotor 1 and having outer ends 8a, 8a, formed by two slanted faces 8n' and 8v. The inner ends 8f of the vanes, form rounded bottom chambers 7a at the radially inner ends of the vane slots 7, 7' and 7". The inner surface of cam ring 2, the outer surface of rotor l, and adjacent vanes form intervane spaces, for example the leading intervane space 12', and the trailing intervane space 10 located on opposite sides of a vane 8'.

The bottom chamber 7a of each vane slot 7, is connected by a bore 9, for example by bore 9', with the trailing intervane space 10', and by a bore 1], for example bore 11' with an intervane space 12, for example the leading intervane space 12.

Adjacent the intervane spaces, the respective bores 9 and 11 are threaded for holding threaded throttle bodies 9b, 11b each of which has a passage 20, as best seen in FIG. 2. The throttle bodies 9b, 11b have at the inner ends thereof, frustro-conical valve seats 90, 110 which cooperate with spherical balls 21 movable in the inner end portions of the bores 9, 9. The ball 21 in bore 11 is shown spaced from the valve seat, and the ball 21 in bore 9' is shown abutting the valve seat due to the flow of fluid from intervane space 12' to intervane space 10'.

In order to prevent that balls 21 drop into the bottom chambers 70, 7a, small openings connect the bores 9', 11' with the common bottom chamber 7a of the respective vane slot 7'. In the frusto-conical valve seats 90, transverse throttling channels 9d, 11d are provided, which, when closed by a ball 29 abutting the respective valve seat, form throttle passages whose total cross section is smaller than the cross section of the throttle passages 20. By selecting the total flow cross sections of the slot 9d, 11d, the magnitude of the pressure prevailing in the bottom chamber 7a, and of the pressure acting on the inner end face 8f of vane 8, is determined.

In the illustrated rotor position, the leading intervane space 12' in the intermediate zone 13 between the end 4b of the suction port 4, and the opposite end a of the pressure port 5 is in communication with the pressure port 5 so that the respective leading intervane space 12' contains pressure fluid at high pressure. The intervane space which trails the vane 8', is still in communication with the low pressure suction port 4 through the port end 46. Due to the different pressures in intervane spaces l2'and 10', fluid flows through throttle passage of the throttle body 11b secured in the bore 11, and presses the respective valve element 21 away from the respective valve seat 11c. The fluid flows then through bottom chamber 7a and into the inner end of bore 77, exerting pressure on valve element 21 to abut valve seat 9c, see also FIG. 2, flowing through the throttle channels 9d and through the respective throttle passage 21 into the intervane space 10' so that fluid flows from the high pressure port end 5a to the low pressure port end 4b.

Since the total cross section of the throttle channels 9d is smaller than the flow cross section of the throttle bore 20, an intermediate pressure prevails in the bottom chamber 7a of the vane slot 7, which is greater than the average pressure of the high and low pressures prevailing in intervane spaces 12 and 10.

The magnitude of the pressure in the bottom chamber 7a acting on the inner end face 8]" of the respective vane 8' is determined by the difference between the effective throttling cross section. The difference between the cross section of throttle passage 20 and the total cross section of all throttling channels 9d determines the pressure in the bottom chamber 70'. The greater the difference is, the greater is the pressure in bottom chamber 7a, and also acting on vane 8.

In order to assure a sealing abutment of the outer end 8a, 8v, 8n on the inner endless slide surface 20 of eccentric cam ring 2, the pressure in bottom chamber 7a acting on the inner end face 8f, must only be slightly greater than the average pressure of the high and low pressures prevailing in the'leading and trailing intervane spaces 12 and 10'. The difference between the effective throttle cross sections can be made small.

When rotor 1 turns farther in clockwise direction out of the illustrated position, the communication of the trailing intervane space 10' with the suction port 4 is terminated since the vane 8" moves beyond the port end 4b. The pressure in the trailing intervane space 10' increases, together with the pressure in the bottom chamber 7'11, since the pressure in the intervane space 10 is no longer negative. The sealing engagement between the outer end 8a' and the inner surface 20 of eccentric cam ring 2 is maintained.

When due to further rotation of rotor 1, both intervane spaces 10' and 12 communicate with the pressure port 5, the vane 8a is balanced, and no fluid flows through the throttling passages.

When the vane 8' has passed the pressure port 5 and moves into the intermediate region 14 between the pressure port end 5b and the suction port end 5a, the pressure in the leading intervane space 12' is reduced, while the pressure of the trailing intervane space 10' corresponds to the pressure prevailing in the pressure port 5. The flow of fluid through the bottom chamber 7a is reversed as compared with the flow during passage through the intermediate zone 13. The reverse flow causes a lifting of ball 21 from valve seat 90, and an abutment of ball 21 on the valve seat 11c, so that the throttling passage 20 of the throttle body 9!), and the throttling channels 11d of the throttle body llb are effective.

The leading and trailing intervane spaces 10, 12 are placed in the region of the suction port 4 during further rotation of the rotor, via pressure acting on vane 8' is again balanced.

The invention is not limited to the disclosed embodiment, and the throttling passages and channels for determining the pressure acting on the inner ends 8f of the vanes, can also be provided in control valve plates.

It will be understood that each of the elements described above, or two or more together, may also find a useful application in other types of hydraulic vane machines differing from the types described above.

While the invention has been illustrated and described as embodied in a hydraulic vane machine with pressure controlled vanes provided with throttles in connecting intervane spaces with a bottom chamber formed in the vane slot by the respective vane, it is not intended to be limited to the details shown, since various modifications and structural changes may be made without departing in any way from the spirit of the present invention.

Without further analysis, the foregoing will so fully reveal the gist of the present invention that others can by applying current knowledge readily adapt it for various applications without omitting features that, from the standpoint of prior art, fairly constitute essential characteristics of the generic or specific aspects of this invention and, therefore, such adaptations should and are intended to be comprehended within the meaning and range of equivalence of the following claims.

What is claimed as new and desired to be protected by Letters Patent is set forth in the appended claims.

I claim:

1. Hydraulic vane machine with pressure controlled vanes, comprising a rotor having a plurality of vane slots; vanes movably mounted in said vane slots and having outer ends projecting from said rotor and inner ends forming bottom chambers in said vane slots; an actuating cam ring surrounding said rotor eccentrically to the axis of said rotor and being engaged by said outer ends of said vanes so that expanding and contracting intervane spaces are formed between said rotor, said cam ring, and pairs of adjacent vanes; a pair of throttle means mounted on said rotor for each vane and having a pair of first ends communicating with said bottom chamber of the respective vane slot, and a pair of second ends; and means for applying different pressures at said second ends and connecting said second ends of each pair of throttle means with a pair of intervane spaces leading and trailing the respective vane, respectively, whereby at different pressuresin the intervane spaces of the respective pair, fluid flows through the respective pair of throttle means and through the respective bottomchamber whereby the respective 'vane is pressed against said cam ring.

2. Hydraulic vane machine as claimed in claim 1, wherein each throttle means includes a throttle passage having a valve seat at said first end, and a valve element cooperating with the respective valve seat for partly closing the respective throttle passage so that fluid flowing through said throttle passages urges one of said valve elements of a pair of throttle means away from the valve seat thereof, and the other valve element against the seat thereof so that the flow of fluid through the respective throttle passage and thereby through the respective pair of throttle means and through the respective bottom chamber is reduced.

3. Hydraulic vane machine as claimed in claim 2, wherein each valve seat is formed with at least one channel communicating with the respective throttle passage and remaining open when the respective valve element is pressed against the valve seat thereof; and wherein the flow cross section of said channel is less than the flow cross section of the respective throttle passage.

4.Hydraulic vane machine as claimed in claim 3,

wherein each valve seat is formed with a plurality of channels; and wherein the total flow cross section of all channels of each valve seat is less than the flow cross section of the respective throttle passage.

,5. Hydraulic vane machine as claimed in claim 4, wherein said channels are transverse to the respective throttle passage; and wherein said valve elements are spherical balls.

6. Hydraulic vane machine as claimed in claim 1, wherein each throttle means includes a throttle passage having a valve seat at said first end, and a valve element cooperating with the respective valve seat for partly closing the respective throttle passage so that fluid flowing through said throttle passages urges one of said valve elements of a pair of throttle means away from the valve seat thereof, and the other valve element against the seat thereof so that the flow of fluid through the respective throttle passage and thereby through the respective pair of throttle means and through the respective bottom chamber is reduced.

7. Hydraulic vane machine as claimed in claim 1, comprising stationary means including two substantially semicircular ports for high pressure fluid and low pressure fluid having two pairs of circumferentially spaced port ends forming between each other two diametrically positioned intermediate zones; and wherein said vanes are circumferentially spaced such equal dis tances that intervane spaces leading and trailing a vane located in the middle of an intermediate zone communicate with said ports, respectively, whereby different pressures prevail at said second ends of the respective pair of throttle means so that the pressure in the respective bottom chamber is intermediate said different pressures.

8. Hydraulic vane machine as claimed in claim 1, wherein said rotor has a bore between each pair of vanes forming an intervane space; and wherein said throttle means are secured in said bores, respectively.

9. Hydraulic vane machine as claimed in claim 8, wherein the throttle means of each pair of throttle means are located in a pair of said bores; and wherein said bores are slanted to the respective vane slot so that the inner ends of said throttle means communicate with the respective bottom chamber, and the outer ends of said throttle means communicate with the leading and trailing intervane spaces. 

1. Hydraulic vane machine with pressure controlled vanes, comprising a rotor having a plurality of vane slots; vanes movably mounted in said vane slots and having outer ends projecting from said rotor and inner ends forming bottom chambers in said vane slots; an actuating cam ring surrounding said rotor eccentrically to the axis of said rotor and being engaged by said oUter ends of said vanes so that expanding and contracting intervane spaces are formed between said rotor, said cam ring, and pairs of adjacent vanes; a pair of throttle means mounted on said rotor for each vane and having a pair of first ends communicating with said bottom chamber of the respective vane slot, and a pair of second ends; and means for applying different pressures at said second ends and connecting said second ends of each pair of throttle means with a pair of intervane spaces leading and trailing the respective vane, respectively, whereby at different pressures in the intervane spaces of the respective pair, fluid flows through the respective pair of throttle means and through the respective bottom chamber whereby the respective vane is pressed against said cam ring.
 2. Hydraulic vane machine as claimed in claim 1, wherein each throttle means includes a throttle passage having a valve seat at said first end, and a valve element cooperating with the respective valve seat for partly closing the respective throttle passage so that fluid flowing through said throttle passages urges one of said valve elements of a pair of throttle means away from the valve seat thereof, and the other valve element against the seat thereof so that the flow of fluid through the respective throttle passage and thereby through the respective pair of throttle means and through the respective bottom chamber is reduced.
 3. Hydraulic vane machine as claimed in claim 2, wherein each valve seat is formed with at least one channel communicating with the respective throttle passage and remaining open when the respective valve element is pressed against the valve seat thereof; and wherein the flow cross section of said channel is less than the flow cross section of the respective throttle passage.
 4. Hydraulic vane machine as claimed in claim 3, wherein each valve seat is formed with a plurality of channels; and wherein the total flow cross section of all channels of each valve seat is less than the flow cross section of the respective throttle passage.
 5. Hydraulic vane machine as claimed in claim 4, wherein said channels are transverse to the respective throttle passage; and wherein said valve elements are spherical balls.
 6. Hydraulic vane machine as claimed in claim 1, wherein each throttle means includes a throttle passage having a valve seat at said first end, and a valve element cooperating with the respective valve seat for partly closing the respective throttle passage so that fluid flowing through said throttle passages urges one of said valve elements of a pair of throttle means away from the valve seat thereof, and the other valve element against the seat thereof so that the flow of fluid through the respective throttle passage and thereby through the respective pair of throttle means and through the respective bottom chamber is reduced.
 7. Hydraulic vane machine as claimed in claim 1, comprising stationary means including two substantially semicircular ports for high pressure fluid and low pressure fluid having two pairs of circumferentially spaced port ends forming between each other two diametrically positioned intermediate zones; and wherein said vanes are circumferentially spaced such equal distances that intervane spaces leading and trailing a vane located in the middle of an intermediate zone communicate with said ports, respectively, whereby different pressures prevail at said second ends of the respective pair of throttle means so that the pressure in the respective bottom chamber is intermediate said different pressures.
 8. Hydraulic vane machine as claimed in claim 1, wherein said rotor has a bore between each pair of vanes forming an intervane space; and wherein said throttle means are secured in said bores, respectively.
 9. Hydraulic vane machine as claimed in claim 8, wherein the throttle means of each pair of throttle means are located in a pair of said bores; and wherein said bores are slanted to the respective vane slot sO that the inner ends of said throttle means communicate with the respective bottom chamber, and the outer ends of said throttle means communicate with the leading and trailing intervane spaces. 